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PIGMENT PROPERTIES
KEROX pigments are known for their excellent quality which is enabled by good compatibility and color uniformity. The primary pigments are selected based on the following properties.
Light Fastness
Excellent light fastness is one of the qualities of KEROX pigments.. Exposure to sunlight does not make them either fade or discolor.
Outdoor Durability
The durability factor of the pigment depends on various external conditions. Some of the environmental conditions that affect the outdoor durability of the pigment include moisture, light, heat and the effect of some pollutants which are found in the environment. It is generally found that darker shades show superior durability when compared to pastel shades. A limited amount of durability is shown by translucent colors.
UV Resistance
UV resistance is another important factor which results in acceleration of physical and chemical degradation of FRP products when constantly exposed to outdoor elements. The degradation usually is higher on the surface of such mouldings. Since the surface erodes rather quickly, protection of FRP moulded outdoor structures is an important aspect which is not to be ignored.
Pigments help in absorption, as well as conversion of UV radiation. They convert the harmful radiation into harmless heat, which in turn prolongs the life of outdoor FRP moulding. The higher the concentration of pigments on the surface, the greater would be the protection offered. A higher loading of pigments therefore ensures protection for a longer period of time.
Heat Resistance
The processing of sheet /dough moulding compounds usually takes place at high temperatures around ranging anywhere from 140 to 160 degrees Celsius or sometimes even more. The heat resistance capabilities of pigments during such applications depend on factors such as temperature, exposure time and oxidizing conditions during the processing procedure. The coloring of such moulding compounds can be achieved through special pigments.
Chemical Resistance
Generally speaking FRP chemical equipments are not using pigments due to extreme environmental conditions. However in cases when the service conditions are known special pigments can be offered.
Electrical Properties
When it comes to electrical applications polyester mouldings are widely used. In such cases special pigments can be offered. These special pigments will have no adverse effects on surface resistivity, dielectric strength, track resistance and various other insulation properties.
Toxicity
specially manufactured, non-toxic pigments can be offered for coloring FRP equipments which are used for either storing or processing of food products.
USAGE LEVEL
The Following levels,based on weight of resin,are recommended.
8- 12% for gelcoat
4-6% for laminates
8-10 % for sheet/dough moulding compounds
1-5 % for translucent sheets
4 -6 % for filled castings
8-10 % for pultrusions.
Under-pigmentation may lead to non-uniformity of colour and other surface defects. Higher pigmentation will provide better uniformity,colour depth, brightness and longer durability.
MIXING INSTRUCTIONS
KEROX pigments tend to readily mix along with polyester resins. In fact small quantities can even be mixed with hand stirring. The slow paddle type mixers available nowadays are the preferred choice since they minimize aeration which takes place during mixing.
A weighed quantity of the pigment is first charged into a mixing vessel.A small quantity of resin is then added and mixed until uniform,when the remainder of the resin is added and mixed.
On no account should a small quantity of the pigment be added to a large bulk of the resin before first thinning.
The accelerator may be added to large pigmented master batches and stored for 24 hours or longer without loss os activity before use.Small lots of pigmented/pre accelerated resin may then be catalysed before use.
Storage Stability
KEROX pigments have execellent stability in storage and minimum guaranteed shelf-life is 6 months.Stroage below250C is recommended for longer shelf life.
Colour Matching
KEROX PIGMENTS can be mixed with one another to obtain intermediate shades. Dark shades present no particular problem, but pastel shades may be difficult.Colours can be matched to customer’s requirements provided the minimum quantity is large.
EPOXY PIGMENTS
Pigments dispersed in polymeric plasticisers are available for colouring epoxy laminates and casting.At 5-10% levels of usage,theplasticizers will have no adverse effect on the cured resin.
Pigments dispersed in liquid epoxy resin can be supplied for special applications.
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